This dissertation constitutes two major sections. In the first major section, a kinetic analysis was established to investigate the electromigration (EM), enhanced intermetallic compound (IMC) growth and void formation for Sn-based Pb-free solder joints to Cu under bump metallization (UBM). The model takes into account the interfacial intermetallic reaction, Cu-Sn interdiffusion, and current stressing. A new approach was developed to derive atomic diffusivities and effective charge numbers based on Simulated Annealing (SA) in conjunction with the kinetic model. The finite difference (FD) kinetic model based on this approach accurately predicted the intermetallic compound growth when compared to empirical observation. The ultimate electromigration failure of the solder joints was caused by extensive void formation at the intermetallic interface. The void formation mechanism was analyzed by modeling the vacancy transport under electromigration. The effects of current density and Cu diffusivity in Sn solder were also investigated with the kinetic model. The second major section describes the integration of Step and Flash Imprint Lithography (S-FIL®) into an industry standard Cu/low-k dual damascene process. The yield on a Back End Of the Line (BEOL) test vehicle that contains standard test structures such as via chains with 120 nm vias was established by electrical tests. S-FIL shows promise as a cost effective solution to patterning sub 45 nm features and is capable of simultaneously patterning two levels of interconnect structures, which provides a low cost BEOL process. The critical processing step in the integration is the reactive ion etching (RIE) process that transfers the multilevel patterns to the inter-level dielectrics (ILD). An in-situ, multistep etch process was developed that gives excellent pattern structures in two industry standard Chemical Vapor Deposited (CVD) low-k dielectrics. The etch process showed excellent pattern fidelity and a wide process window. Electrical testing was conducted on the test vehicle to show that this process renders high yield and consistent via resistance. Discussions of the failure behaviors that are characteristic to the use of S-FIL are provided. / text

La présente étude concerne le comportement hydromécanique des matériaux compactés à base de bentonite pour le stockage des déchets radioactifs en grande profondeur. Trois matériaux candidats ont été étudiés : la bentonite (MX80) pure, le mélange bentonite/argilite broyée et le mélange bentonite/sable. Une étude expérimentale sur la pression de gonflement du mélange bentonite/argilite a été premièrement réalisée. Cette étude a mis en évidence l'effet de la salinité de l'eau, de la procédure et la durée d'hydratation, du pré-existant vide technologique et des méthodes expérimentales. Une importante relation entre la pression de gonflement et la densité sèche finale de la bentonite a été élaborée. Ensuite, des essais de rétention d'eau, des essais d'hydratation et des essais oedométriques à succion contrôlée ont été réalisés sur des échantillons à différentes porosités tout en considérant la présence du vide technologique. En introduisant les paramètres comme indice des vides de la bentonite et le ratio volume d'eau, une analyse globale des effets des vides sur la réponse hydromécanique de la barrière ouvragée a été effectuée. Pour obtenir un meilleur aperçu de l'évolution de l'étanchéité dans le cas de vide technologique, l'effet de densité sèche finale (densité après fermeture de vide technologique) et du temps d'hydratation sur la microstructure a été, de même, étudié. La perméabilité de ce matériau à l'état non saturé a été ensuite étudiée en réalisant des essais de rétention d'eau et d'infiltration ainsi que par des observations de la microstructure. Les résultats obtenus ont permis de relier la variation de la conductivité hydraulique non saturée aux changements de la microstructure. Une expérimentation en modèle réduit reproduisant à une échelle 1/10ème les essais in-situ (SEALEX) a été effectuée, et cela pour étudier la reprise des vides à long terme d'un mélange compacté bentonite/sable, tout en considérant la présence d'un vide technologique. Les résultats ont été utilisés pour interpréter les observations de l'essai in situ. A une échelle de temps réduite, cette étude fournit des informations utiles pour estimer la durée et l'efficacité de la conception en place. Finalement, les données expérimentales obtenues dans le laboratoire sur le mélange bentonite/sable ont été interprétées dans le cadre du modèle de Barcelone (BExM). Après comparaison des résultats expérimentaux avec le modèle, les performances et les limitations du modèle ont été analysées / This study deals with the hydro-mechanical behaviour of compacted bentonite-based materials used as sealing materials in high-level radioactive waste repositories. The pure MX80 bentontie, mixtures of MX80/crushed claystone and MX80/sand were used in the investigation. An experimental study on the swelling pressure of the bentonite-based materials was first performed. The results evidenced the effects of water chemistry, hydration procedure and duration, pre-existing technological void and experimental methods. Emphasis was put on the relationship between the swelling pressure and the final dry density of bentonite. Afterwards, the water retention test, hydration test and suction controlled oedometer test were conducted on samples with different voids including the technological void and the void inside the soil. By introducing the parameters as bentonite void ratio and water volume ratio, an overall analysis of the effects of voids on the hydro-mechanical response of the compacted material was performed. To get better insight into the seal evolution in case of technological void, the effects of final dry density and hydration time on the microstructure features were also characterized. Then, the hydraulic properties under unsaturated state were investigated by carrying out water retention test and infiltration test as well as the microstructure observation. The results obtained allowed relating the variation of hydraulic conductivity to the microstructure changes. A small scale (1/10) mock up test of the SEALEX in situ experiment was also performed to study the recovery capacity of bentonite-based material with consideration of a technological void. The results were used for interpreting the in-situ observations. With a reduced time scale, it provides useful information for estimating the saturation duration and sealing effectiveness of the field design. Finally, the experimental data obtained in the laboratory on bentonite/sand mixture were interpreted in the framework of the Barcelona Expansive Model (BExM). By comparing the model with the experimental results, the performance and limitation of the model were analyzed

Consolatio vacui (joy, deligt, consolation of void) is a conceptual piece exploring the idea of void and emptiness in contrast to the concept „horror vacui,“ which is wide-spread in the subconsciousness of the west culture. The piece deals with void as a field of possibilities, as a space without which there were no particular things. These questions are examined first in general, then in the field of objects and eventually in the specific field of book, asking the questions of ways and effects of communication, relationship of sign and void, purpose of empty space in the book (and in general). The piece consists of 24 books, 99 mostly empty pages each, which symbolizes the wide field of possible consideration of the issues solved in each book on one or a few pages. The 24th book is a summary of all the ideas with commentary.

O desenvolvimento de um concreto de alto desempenho aplicado a sistemas de processamento e armazenagem de alimentos em baixas temperaturas teve por objetivo atender às indústrias de alimentos no Brasil que se utilizam da tecnologia do frio em seu processo industrial. A hegemonia mundial do mercado de carnes é brasileira, sendo que nossas indústrias são responsáveis por 33% desse mercado. A ausência de estudos para aprimorar e tornar as plantas industriais mais duráveis e condizentes com a importância do setor foi determinante na delineação do tema desta tese. Desenvolveu-se um concreto de alto desempenho frente às possíveis situações em uma planta industrial: baixas temperaturas em ambientes secos e baixas temperaturas em ambientes sujeitos à umidade. A temperatura mínima a qual foram submetidos os concretos analisados foi de 35°C. O método de dosagem e as diretrizes calcadas no reforço da matriz da pasta de cimento e refinamento de poros mostraram-se como uma alternativa para vencer as agressividades causadas pelas baixas temperaturas ao concreto. Até então, estudos sugeriam um sistema de ar cujos vazios teriam diâmetros em torno de 250 µm espaçados com esta mesma distância entre eles e com conteúdo de 6±1% para a proteção de concretos expostos a baixas temperaturas. A produção de um concreto coeso, com teor de ar de 3,5%, poros com diâmetro médio de 0,02 µm e com área específica de 2,84m²/g, provaram ser duráveis quando expostos ao congelamento e a ciclos de gelo e degelo. O fator de durabilidade para esses concretos foi de 97%. Além da durabilidade, o projeto de dosagem contemplou o aspecto econômico, produzindo 1MPa com 7,8 kg de cimento por metro cúbico de concreto. Os resultados foram obtidos por meio de ensaios dinâmicos, microscopia eletrônica de varredura, porosimetria por intrusão de mercúrio, absorção de água por imersão, além dos ensaios mecânicos de resistência à compressão, à tração na flexão e módulo de elasticidade. / Brazil has rapidly emerged as one of the world\'s leading meat exporters, being responsible by 33% of this market. In face of that, a high performance concrete (HPC), that can be applied to storage and processing system buildings at low temperatures, has been developed with the aim of answering the needs of brazilian food manufacturers that use cooling technology during industrial process. The lack of studies to improve industrial plants and make them more durable was determinant to delineate this thesis subject. A high performance concrete was designed to resist to low temperatures at dry environments as well as at moist ones. Concrete was exposed to a target temperature of -35°C. The dosage method and the guidelines based on the strengthening of bulk cement and the porous refinement showed to be an alternative to overcome the aggressiveness caused by low temperatures to concrete. To this day, studies have suggested air voids systems to protect concrete from low temperature effects. According to them, the air voids should have about 250 µm of diameter, spaced from each other this same distance and with an air content of 6±1%. However, making a cohesive concrete, with 3,5% of air content and an average diameter porous of 0,02 µm with an specific surface of 2,84m²/g, resulted in a durable concrete, even when exposed to frost / thawing cycles. The durability factor of these concretes achieved 97%. Besides durability, the dosage design brought economical advantages, producing 1 MPa with 7,8 kg of cement per cubic meter of concrete. The results were obtained through dynamic tests, scanning electron microscopy, mercury intrusion porosimetry and water absorption by immersion. In addition, tests of compression, tension strength and elastic modulus were carried out.

A Agência Internacional de Energia Atômica (IAEA - \"International Atomic Energy Agency\") vem incentivando o desenvolvimento de sistemas passivos de refrigeração em plantas nucleares visando a simplificação e o incremento da confiabilidade em funções essenciais de segurança nos projetos de uma próxima geração de reatores nucleares refrigerados a água. O principal fundamento desses sistemas é o emprego da circulação natural como sistema de segurança aplicável em operações de desligamento do reator para manutenção ou na ocorrência de acidentes. A circulação natural é um fenômeno que surge em virtude do gradiente de temperatura em pontos diferentes do circuito de refrigeração. Em condições extremas de estabilidade têm-se o estabelecimento do escoamento bifásico gás/líquido podendo configurar-se segundo diferentes regimes. A fração de vazio é reconhecida como um dos parâmetros chave na predição da ocorrência de instabilidades do escoamento bifásico. Apresenta-se neste trabalho uma inovadora metodologia para estimativa da fração de vazio a partir de imagens digitais capturadas diretamente de circuitos experimentais que geram o escoamento bifásico. O método é baseado na aquisição de imagens, com controle da profundidade de campo, de uma seção do Circuito de Circulação Natural (CCN) presente no IPEN/CNEN-SP. A imagem é segmentada com base na inferência fuzzy de diferentes parâmetros de segmentação e ajustada ao foco utilizado na sua aquisição. Ela é varrida de um modo inédito e iterativo, utilizando máscaras de diferentes tamanhos integrando um conjunto de redes neurais com a Transformada Randomizada de Hough. Cada diferente tamanho de máscara é escolhido de acordo com os tamanhos das bolhas que são os objetos de interesse. O volume da bolha é estimado baseado em sua projeção plana capturada nas imagens digitais. O cálculo da fração de vazio considera o volume da seção geométrica do escoamento no tubo de vidro cilíndrico e a profundidade de campo utilizada e nos parâmetros geométricos inferidos para cada bolha detectada. Os resultados mostraram que a integração entre o conjunto de redes neurais e a Transformada Randomizada de Hough aumentaram a robustez das estimativas do sistema. / The International Atomic Energy Agency (IAEA) has been encouraging the use of passive cooling systems in new designs of nuclear power plants. Next nuclear reactor generations are intended to possess simpler and robust safety functions. Natural circulation based systems hold an undoubtedly prominent position among these. Natural circulation phenomenon occurrence depends only on the existence of refrigerant liquid temperature gradient in different sections of the plant refrigerator circuit. The study of limit conditions for these systems has led to instability behavior analysis where many different two-phase flow patterns are present. Void fraction is a key parameter in thermal transfer analysis of theses flow instability conditions. This works presents a new method to estimate void fraction from digital images captured at an experimental two-phase flow circuit. The method is primarily based on depth-of-field controlled image acquisition of a section of a closed loop of natural circulating water through cylindrical glass tubes. This loop is called Natural Circulation Facility (NCF) and is located at Nuclear and Engineering Research Institute in Brazil (IPEN/CNEN-SP). Image is segmented based on fuzzy inference of different segmentation parameters and adjusted to image acquisition focus. The image is then scanned in an inedited way using different-sized masks integrating a set of different artificial neural networks with a modified Randomized Hough Transform. Each different mask size is chosen in accordance to bubble sizes which are objects of interest. The bubble volume is estimated based on two-dimensional projection sizing based on digitally acquired images. Void fraction calculation takes into account the volume of the geometrical section of flow inside cylindrical glass tube considering used depth-of-field. It is also based on the summed bubble geometrical parameters inferred for each detected bubble. The results have shown that integration between artificial-neural-net sets and Randomized Hough Transforms increase system estimations robustness.

Made available in DSpace on 2016-04-26T20:25:26Z (GMT). No. of bitstreams: 1 HAMID C B JR.pdf: 1174776 bytes, checksum: 128318ada1c92e63a1f02c4e4fac0fee (MD5) Previous issue date: 2007-04-27 / This work verifies the possibility of typically void transactions having their effects preserved in spite of the nullity of the transaction. It starts with the study of legal transactions as regards their existence, in a summary fashion, their validity and effectiveness. Afterwards the hypothesis of absolute nullity and mere voidability are studied in order to verify which criterion could justify the preservation of the typically void transactions. In the first chapters the examination of validity and the effects of the legal transaction is done with the study of some aspects concerning the existence. The study has the objective of identifying the elements and the conditions of effectiveness. In order to reach the specific studies of the void legal transaction, the distinctions between nullity and voidability and the nature of the referred invalidity have been examined. In this context, each situation foreseen in the Civil Code as a hypothesis of nullity and voidability has been analyzed, as well as some characteristics of the law suits filed in order to dissolve or declare the nullity of the transaction. The direct and indirect effects of the void legal transactions and the principles that can justify their preservation are analyzed and confronted with their purpose to the institute. In a proper chapter, the situations in which the effectiveness of a typically void transaction could be preserved in light of the applicability of principles and values that could justify such conclusion have been studied. In the final chapter presents jurisprudence that demonstrates the existence of concrete situations to which the conclusions of this work are applied / O trabalho objetiva verificar a possibilidade de negócios tipicamente nulos, apesar da nulidade, terem seus efeitos preservados. Para tanto, inicia com o estudo dos negócios jurídicos nos planos da existência, de modo breve, da validade e da eficácia. Posteriormente, estuda as hipóteses de nulidade e anulabilidade, para então verificar quais critérios podem justificar a preservação dos negócios tipicamente nulos. Nos capítulos iniciais, examina a validade e os efeitos dos negócio jurídico, com o estudo de alguns aspectos relativos à existência. Cuida de identificar seus elementos e suas condições de eficácia. Para alcançar o estudo específico dos efeitos do negócio nulo, examina as distinções entre nulidades e anulabilidadese e a natureza dessas invalidades. Nesse contexto, cada uma das situações previstas no Código Civil como hipótese de nulidade e anulabilidade é analisada, assim como determinadas características das ações ajuizadas com o fim de desconstituir ou declarar a nulidade do negócio. Os efeitos dos negócios inválidos, indiretos e diretos, e os princípios que podem justificar a preservação deles são analisados, em confronto com sua utilidade para o instituto. Em capítulo próprio, examina as situações em que a eficácia de um negócio tipicamente nulo poderia ser preservada, em face da incidência de princípios e valores que pudessem justificar tal conclusão. No capítulo final, apresenta jurisprudência que demonstra a existência de situações concretas, casuísticas, que se sujeitam às conclusões a que chegou

Embora seja uma técnica tradicional, empregada largamente em processos industriais, a operação unitária de aeração pode ser otimizada ao se utilizar modelos matemáticos que descrevam seu comportamento hidrodinâmico. Diversas equações se prestam a esse fim, no entanto, avanços tecnológicos, tanto no campo instrumental como computacional, permitiram a obtenção de equações mais realísticas e abrangentes. Neste trabalho foram ajustadas e avaliadas equações para descrever três importantes parâmetros envolvidos na transferência de oxigênio em meio hídrico: coeficiente volumétrico de transferência de massa, fração de vazios e velocidade ascensional de bolhas. Para tanto, ademais da utilização de conceitos teóricos amplamente difundidos no meio acadêmico, empregou-se um conjunto de dados já existente. Essa combinação permitiu a avaliação e aproximação das equações teóricas à realidade experimental através de coeficientes de ajuste empíricos. Foram obtidos os seguintes resultados: a) revisão bibliográfica e sugestão da correlação que melhor descreve o coeficiente volumétrico de transferência de massa; b) correlação que descreve a fração de vazios, a partir da analise da concentração de bolhas segundo distribuições gaussianas; c) correlação que descreve a velocidade ascensional de bolhas em plumas. A complexidade de cada parâmetro obtido deixou clara a importância da análise isolada, precedendo a convolução dos mesmos em um único modelo, pois embora as resposta e recomendações apresentadas não forneçam conclusões definitivas sobre todos os aspectos envolvidos na transferência de oxigênio em meio hídrico, suas considerações pontuais contribuem sobremaneira ao domínio do fenômeno global, beneficiando modelagens matemáticas futuras. / Although it is a traditional technique, widely employed in industrial processes, the unit operation of aeration can be optimized when resorting to mathematical models which describe their hydrodynamic behavior. A range of equations lends itself to this purpose, however, technological advances both in the instrumental as computational field, allowed the achievement of equations more realistic and comprehensives. In this study were adjusted and evaluated equations to describe three important parameters involved in the oxygen transfer in the hydric medium: volumetric mass transfer coefficient, void fraction and upflow bubble velocity. To this end, besides the use of theoretical concepts widely disseminated in the academic literature, it was employed a set of already existing data. This combination allowed the evaluation and approximation of theoretical equations to experimental reality by means of empirical adjustment coefficients. Were obtained the following results: a) literature review and suggestion of the best correlation which describes the volumetric mass transfer coefficient, b) correlation which describes the fraction of voids, from the analysis of the concentration of bubbles by Gaussian distributions, c) correlation which describes the upflow velocity of swarms of bubbles. The complexity of each parameter obtained made clear the importance of the isolated analysis, preceding the convolution of them in a single model because although the answers and recommendations given fail to supply definitive conclusions on all aspects involved in the transfer of oxygen in hydric medium, their specific considerations contribute to the knowledge of the global phenomenon, benefiting deeply future mathematical models.

As Vibrações Induzidas por Escoamentos (VIEs) são dos problemas dinâmicos mais importantes no projeto de trocadores de calor de tipo carcaça e tubos. Esta interação fluido - estrutura pode gerar vibrações de grande amplitude dos tubos ou partes internas do equipamento, o que pode provocar o impacto entre componentes e até falha por fadiga. Várias bancadas experimentais têm sido construídas para o estudo desta interação fluido - estrutura, no entanto, alguns mecanismos de vibração, principalmente aqueles relacionados com escoamentos bifásicos, não são completamente compreendidos. Portanto, neste trabalho, o projeto de uma estrutura dinâmica para o estudo das vibrações induzidas por escoamento bifásico é apresentado. Esta estrutura é composta por um sistema de fios de aço tensionados que permitem que a primeira frequência de ressonância do tubo seja sintonizada. O tubo instrumentado foi instalado numa seção de testes de tubos rígidos em configuração triangular normal com uma razão de passo transversal e diâmetro de 1,26. Os resultados experimentais foram contrastados com uma modelagem teórica desenvolvida para esta estrutura dinâmica. Pôde-se verificar que a primeira frequência de ressonância e seu fator de amortecimento coincidem com os valores estimados pelo modelo, enquanto que a segunda frequência de ressonância apresenta valor teórico 6,6% maior do que o experimental. A seguir, um estudo experimental no ar foi desenvolvido para o reconhecimento dos modos de vibração e as frequências de ressonância da estrutura dinâmica. O fator de amortecimento no ar também foi estimado, o método de Kennedy - Pancu combinado com o algoritmo ERA foi usado para este fim. Assim que a primeira frequência de ressonância foi reconhecida e sintonizada, testes em escoamentos de água foram realizados. A influência da velocidade do escoamento monofásico de água na amplitude de vibração e nas características da Densidade Espectral (PSD) de aceleração foi analisada. Finalmente, testes em escoamento bifásico foram feitos, a sensibilidade do tubo ao escoamento bifásico fica evidente quando analisadas as amplitudes nas PSDs. Além disso, a influência da fração de vazio na amplitude de vibração e no fator de amortecimento foi revisada, no entanto, resultados de estudos anteriores não foram conferidos pelo alto amortecimento concentrado introduzido por alguns elementos construtivos utilizados. / Flow - Induced Vibration (FIV) is the most critical dynamic issue in the design of heat exchangers. This fluid - structure phenomenon may generate high amplitude vibration of tubes or structural parts, which may lead to impacts between internal components or even failure due to fatigue. Many test benches have been constructed to study this fluid - structure interactions, however, some vibration mechanisms, mostly those related to multiphase flow, are not yet fully understood. Therefore, in this work, the design of a dynamic structure for the study of multiphase flow induced vibration is presented. This structure is composed by a system of tensioned piano wires that allow the first natural frequency of the instrumented tube to be calibrated. The tube was installed in a rigid bundle configured in a normal triangular pattern with pitch-todiameter ratio of 1.26. Then, an experimental study in air environment was performed aiming at addressing the mode shapes and resonance frequencies of the dynamic structure. The damping ratio in air environment was also estimated, the Kennedy - Pancu method in combination with the Eigensystem Realization Algorithm have been used to that purpose. Experimental results in air were compared with a theoretical model. The first resonance frequency and its damping factor presented a good agreement with the model, while the second resonance frequency deviated some 6,6% from the predicted value. Tests in water and multiphase flow were also performed. The influence of water flow velocity on vibration amplitudes and on the Power Spectrum Densities (PSDs) has been analyzed. Finally, tests for two - phase water/air flow were carried out; the tube sensitivity to multiphase flow is evident when the vibration level in acceleration PSDs is by analyzed. Also, the influence of void fraction on vibration amplitude and damping ratio have been addressed, however, previous studies could not be validated due to the high damping introduced by some constructive elements of the structure.

L’évanescence suppose un état de précarité qui se nourrit de sa propre incomplétude. Le corps qui s’éthérise est en permanente déperdition de matérialité et d’énergie, ce qui amènera le détachement de la conscience. L’acheminement de l’état « tout-corps » à celui de « dé-corps » passe par trois régimes visuels : par l’opacité, associée à la pierre et à la figure de Thanatos, par la translucidité, qui concerne la chair et le feu érotique et, enfin, par la transparence du verre et de l’air, marquant l’entrée sur les territoires de Narcisse. Le thème du corps évanescent est développé autour de ces trois axes selon une logique centrée sur l’existence d’un seuil – décliné comme mur opaque, paroi organique translucide ou écran transparent. Ce seuil signale la transgression d’ordres et d’interdits. Lors du passage, le corps perd graduellement son ancrage dans la réalité concrète, qui s’estompe à vite allure pour faire place à un complexe espace-temps construit graduellement, dans le malheur de la maladie et de la mort ou dans la joie de la projection heureuse. Le corps évanescent tend vers un ailleurs qui s’organise à mesure que le premier s’efface. Ce double conditionnement s’accompagne d’innombrables régressions temporelles qui réverbèrent au niveau de la conscience incorporée sous la forme de la fissure qui entraîne le détachement. Sous le régime de la pierre l’évanescence se cristallise autour de l’image de la statue qui parcourt le trajet symbolique entre figement et vivification. Le marbre, le plâtre et le sable sont les trois motifs qui expriment l’idée de fragilisation de la matière. Le retour à la vie se prolonge dans la tiédeur de la chair réchauffée. Alors qu’elle atteint le seuil de la liquéfaction dans la fugue érotique, l’intensité de la sensation commence à diminuer, ce qui amène à un nouveau refroidissement. Dans le domaine de la transparence le corps subit des formes de détachement selon une logique qui va de la réflexion dans le miroir en tant qu’expression d’un moi naissant à l’extrême affaiblissement du caractère réfléchissant qui altère l’image de soi. Fenêtre, vitrine et écran sous-tendent l’effacement sous le régime de la transparence tout en créant l’illusion d’une intériorité. Comble du processus évanescent, le corps éthérique est mis en rapport avec l’ineffable de l’élément aérien. Cette forme de corporalité ultime exprime le détachement de la conscience, dans la joie comme dans la souffrance. Elle décrit un état de précarité absolue, qui met en avant le fait que tout en se délivrant de ses amarres matérielles la conscience tend à conserver un engramme qui assure la réincorporation, et avec elle, la survie. L’envol, le survol et la descente décrivent trois formes d’évanescence « aérienne » qui marquent le retour symbolique à l’opacité à travers des images d’épaississement : par les motifs de la vapeur, du brouillard ou de la nuit « polie » on est ramené au point de départ de la réflexion. L’histoire du corps évanescent, qui commence et achève par des images de la mort, est également l’histoire d’un continuel retour à la vie, aux forces pulsionnelles, à l’euphorie de se sentir vivant. / The vanishing body depicts a state of extreme precariousness and reveals a progressive loss of substance and vitality which results in the disembodiment of the conscience. The way from being “all body” to being “out-of-body” is hallmarked by three visual categories, each one being assigned a certain classical element: stone, for opacity (the territory of Thanatos), erotic fire for the flesh representing translucency and air and glass for transparency, reminding Narcissus. In this structure water is always the transversal element. The theme is therefore sustained by a network of thresholds such as: the wall, the organic layer and the transparent or invisible screen. With every threshold comes the idea of transgression. Passing into another state or dimension interrupts the contact with reality which fades swiftly away and makes room for another time-space configuration gradually defined by death and illness, by joy and thrilling giddiness. The vanishing body tends to inhabit a no man’s land ever more present as the first one fades away. It is thus submitted to various temporal regressions which concern the embodied consciousness and evolves as a “crack” finally producing the separation body-conscience. Within the realms of Thanatos and the stone the evanescence concerns the representation of the statue which stiffens and then recovers the “flesh-state” progressively. The marble, the plaster and the sand present themselves as three “stages” of dematerialization. Coming back to life means entering a state of tepidness of the revived flesh. As the sexual temperature increases it reaches a threshold of erotic liquefaction which then diminishes to a new form of symbolic coldness represented by physical decay and loss of sexual interest. In the field of transparency the body suffers several forms of detachment stretching from the mirror reflection as expression of a newly-born ego to the extreme weakening of the reflexivity which alters the sense of self. Window, window display and transparent shield underlie the self-effacement and create the (illusion of) inhabitable space.Peak of the vanishing process, the ethereal body is finally connected to the air as classical element. This ultimate form of corporeality express the disembodiment of the conscience in symbolic projections of both joy and suffering. It shows a state of absolute precariousness which points out the fact that by loosening the grip on the immediate reality the consciousness tends to gradually build up an engram of the body which ensures the reincorporation and by that, the survival. The take-off, the overflight and the landing describe three forms of “aerial” vanishing which states a symbolic return to opacity declined through images of densification: the steam, the fog, and the “polished” opacity of the night represent a comeback to the starting point of reflection. The story of the vanishing body, which starts and ends through images of death, is nevertheless the story of the continuous return to life and its possibilities.

The rapid depletion of hydrocarbon fields around the world has led the industry to search for these resources in ever increasing water depths. In this context, the large diameter (D > 100mm) vertical riser has become a subject of great interest. In this research work, a major investigation was undertaken to determine the two phase flow hydrodynamics in a 254mm vertical riser. Two types of experiments were performed for range of air-water superficial velocities. The first experimental campaign addresses the issue of the two gas injector’s performances (conventional vs. novel design gas injector) in the large diameter vertical riser. The experimental results show that the novel design gas injector should be the preferential choice. The second set of the experimental work investigates the two phase flow hydrodynamics in the vertical riser in detail. The two phase flow patterns and their transitions were identified by combination of visual observations and statistical features. Based on the results, the experimental flow regime map was developed and compared with the existing vertical upflow regime maps/models. None of the flow regime transition models adequately predicted the flow regimes transitions in large diameter vertical risers as a whole. In this regard, the Taitel et al. (1980) bubble to slug flow transition model has been modified for large diameter vertical upflow conditions, based on the physical mechanism observed. The general trends of modified criteria agreed well with the current and other large diameter experimental results. The effect of upstream conditions on the vertical riser flow behaviour was also investigated in detail by two different inlet configurations (i) near riser base injection and (ii) upstream flowline injection. It was found that no significant differences exist in flow behaviour at low air-water superficial velocities for both the inlet configuration, at high air-water superficial velocities, the intermittent flow behavior in flowline influences the riser flow pattern characteristics and thereby controls the riser dynamics. It is found that liquid slugs from the flowline naturally dissipate to some extent in the riser as a consequence of compression of succeeding bubble that rapidly expands and break through the liquid slug preceding it when it enters the riser. The experimental work corroborates the general consensus that slug flow does not exist in large diameter vertical upflow condition. Experimental data has been further compared to increase the confidence on the existing two phase flow knowledge on large diameter vertical riser: (a) by comparing with other experimental studies on large diameter vertical upflow in which generally, a good agreement was found, (b) by assessing the predictive capability of void fraction correlations/pressure gradient methods. The important implication of this assessment is that the mechanistic approach based on specific flow regime in determining the void fraction and pressure gradient is more successful than conventional empirical based approaches. The assessment also proposes a proposed set a of flow regime specific correlations that recommends void fraction correlations based on their performances in the individual flow regimes. Finally, a numerical model to study the hydrodynamic behaviour in the large diameter horizontal flowline-vertical riser system is developed using multiphase flow simulator OLGA. The simulated results show satisfactory agreement for the stable flows while discrepancies were noted for highly intermittent flows. The real time boundary application was partially successful in qualitatively reproducing the trends. The discrepancies between the predicted results and experimental data are likely to be related to the incorrect closure relations used based on incorrect flow regimes predictions. The existence of the multiple roots in the OLGA code is also reported for the first time.